There are many types of sweeping machines for removing various types of debris from a surface, such as the ground, a floor or a parking lot. Many of these sweeping machines use a rotating cylindrical brush to contact the surface being swept. The rotating cylindrical brush is used to lift various types of debris from the floor or surface and throw it into a debris hopper located near the rotating cylindrical brush. The machine moves the rotating cylindrical brush over the surface being swept. The rotational velocity of the cylindrical brush produces a velocity at the ends of the brush that differs from the velocity of the machine as it moves over the surface being swept. The brush can be rotated in either direction. There are many types of sweepers. Two types of sweepers are forward throw sweeper and indirect throw sweepers. Forward throw sweepers use a brush rotated backward with respect to the travel of the sweeping. The debris is thrown forward and collected in a container which is forward of the brush. Indirect throw or over-the-top sweepers use a brush rotated in either direction with a debris container located behind the brush with respect to the direction of travel.
Sweeping machines are used in a variety of environments. For example, some sweeping machines remove debris from roads and streets. Others are used to remove debris from parking lots and others are used to remove debris from factory floors. In short, there are many applications for sweeping machines. Sweeping machines also remove different types of debris. Certain design considerations can be employed to enhance a sweeping machine's ability to pick up or remove certain types of debris.
One such design consideration is referred to as conformance. Conformance is the amount of contact between the rotating cylindrical brush and the surface being swept. High conformance is needed to remove sand, for example. The most effective sweeping machines are generally specifically designed for a particular surface and removal of a particular type of debris.
Of course, one of the most important design considerations is the design of the brush. Brushes can be designed for very specific purposes. For example, in U.S. Pat. No. 4,586,211 the brush is adapted to sweep tile floors. Some of the bristles on the brush in U.S. Pat. No. 4,586,211 are arranged in a plurality of circular rows. The dimension between specific rows of the brush are spaced from one another along the fall length of the core of the brush at the same dimension as either the lengthwise or widthwise dimension of the tiles. The bristles can be made of any of the various types of brush fill materials, which include fibers of plant or animal origin, synthetic filaments, metallic materials, or composite filaments.
Most sweeping environments do not lend themselves to sweeping just one kind of debris or for use in one specialized environment such as the tile sweeper mentioned above. The most challenging designs are those for picking up a variety of debris in one of several environments. In most sweeping environments, it is desirable to be able to pick up all sorts of debris. One difficulty is designing a sweeping machine capable of picking up a wide variety of debris, from light litter, mil-spec hardware, containers, all the way to bulky debris and debris with mixed aspect ratios. A brush that picks up heavy debris is often less effective at picking up light litter, sand and fine particles.
Most brushes for use in a more generalized setting have problems. Some common problems are trailing and poor pickup of light litter. Trailing occurs when debris migrates to a certain area or position on the brush, such as an outside edge and then escapes. The result is a trail of debris, such as sand, that occurs at one location on the brush. Another common problem is poor pickup. It is not uncommon with some current brush and sweeper designs to have to use multiple sweeping passes in order to do an acceptable level of cleaning.
Paper or light litter generally requires a favorable air flow in order to be picked up effectively. In many instances, a turbulent air flow occurs toward the front of a rotating cylindrical brush making light litter difficult to pick up. The turbulent air flow tends to blow the trash around in front of the sweeping machine which makes it difficult to pick up.
A need exists for a sweeping machine that will efficiently sweep all types of debris, such as sand and gravel, light litter, mil-spec hardware, containers, bulky debris and debris with mixed aspect ratios. There is also a need for a sweeping machine that will consistently pick up varying types of debris on a variety of surfaces and one that limits axial migration of debris toward the ends of a rotating cylindrical brush. There is also a need for a brush that minimizes trailing. There is a further need for a sweeping machine that is smooth and stable during its operation.